1. Field of the Invention
The present invention relates to a safely device for an electric glass-winder of a vehicle of the type employing a cable driving the glass by means of a motor and mounted to slide along a guide rail.
2. Description of the Related Art
There are at present three types of glass-winders in automobile vehicles, namely those employing a rack-type cable, those employing a twisted or Borden cable, and those employing an arm and a toothed sector. The invention concerns the first two types of glass-winders.
When an obstacle lies in the path of the glass when closing the window, the system must become aware of the presence of an abnormal phenomenon and, if the force on the glass exceeds a limit value, the glass must not continue its travel but stop and at least release the applied force. This release of the force may be achieved either by releasing the glass which descends under the effect of a small force or the effect of its own weight if the friction in the lateral seal so permits, or by reversing the direction of motion of the glass which is then forced to descend.
To solve this problem, various electric and electromechanical safety devices have been proposed, but they present, among other drawbacks, the drawback of being relatively costly owing to their complexity. This high manufacturing cost is obviously an obstacle to their widespread use.